JPS5922324A - Electron beam drawing method - Google Patents

Abstract

PURPOSE:To prevent a pattern from generation of a constriction and curtailment of size, etc., and to contrive to enhance precision of drawing by a method wherein drawing is performed according to data of frames having enlanged widths thereof. CONSTITUTION:The enlanged frames 6l-6n lengthened by width by DELTA on both the sides of the direction to cross at right angles with longitudinal direction thereof are set to respective frames 2l-2n. At this time, width DELTA is equalized to inclination width of the profile of the electron beam, namely to the minimum beam width. When the pattern to be drawn is drawn according to data of the enlanged frames thereof, because the drawing pattern in the neighborhood of the boundary of the frame is exposed double, reduction of the dose at the starting point and the finishing point of scanning, and moreover at the extremely small size beam, special reduction of the dose, etc., can be prevented from occuring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a mask scanning electron beam writing method.

[Technical burden of the invention and its problems]

Recently, fine particles have been applied to samples such as semiconductor wafers and masks.
Various electron beam lithography devices have been developed to form turns. In electron beam lithography equipment,
Due to the characteristics of the electron optical system, which is the main component, it is difficult to accurately draw the entire surface of a large sample while the sample is stopped. For this purpose, as shown in Fig. 1, the drawing area of the sample 1 is divided into short-shaped frames 2, and while moving the sample I in the longitudinal direction of the frames 2 (X direction in the figure), A so-called raster scan method is employed in which the electron beam 3 is deflected and scanned in the Y direction in the figure. In this method, each time the drawing of one frame 2 is completed, the sample is moved in steps of 1 to n frames in the beam scanning direction X, and a new frame 2 is drawn in the same manner as before.

By repeating this operation, a desired pattern is drawn on the entire drawing area of the sample I.

In the figure, 4 indicates a scanning deflection plate, and 5 indicates a chip.

By the way, the electron beam profile shown in Figure 2 (a)
As shown in (b), it has a finite slope (usually this width is 10 [-:] - 90 [chi] and 0.2 to 0.5 [μm]).
degree), which appears as a dose distribution slope over the imaged area of the sample. Note that FIG. 1(-) shows the profile of a single beam, and FIG. 1(b) shows the profile of a shaped beam. For this reason, especially in the case of the rask scan method, the dose amount is low at the start and end points of the pattern to be drawn.

This is equivalent to effectively making the slope of the dose distribution gentler.

For these reasons, the conventional drawing method using the rask scan method has the following problems. That is, when the arm turn (pattern to be drawn) as shown in FIG. 3(a) is drawn as shown in FIG. 3(b), the actual drawn pattern (pattern after development) as shown in FIG. ), a constriction occurs near the frame boundary P.

Furthermore, when a pattern as shown in FIG. 40 is drawn as shown in FIG. 4(b), the actual drawing i as shown in FIG. 4(e)
The dimension of 4 turns becomes shorter. The occurrence of such constriction and shortening of the pattern size has been a major factor in reducing the drawing accuracy.

[Purpose of the invention]

An object of the present invention is to provide an electron beam lithography method that can prevent pattern constriction and dimension shortening caused by a decrease in dose at frame boundaries, and can improve lithography accuracy.

[Summary of the invention]

The gist of the present invention is that, in order to prevent the dose from decreasing at the frame boundary, data is drawn on an enlarged frame whose width has been expanded, and the area near the frame boundary is double exposed. The present invention provides an electron beam drawing method in which a drawing area is divided into rectangular frames and drawing is performed by rask scanning an electron beam in a direction perpendicular to the longitudinal direction of the frame at the border of the frame. In this method, an enlarged frame is set in advance with a predetermined width Δ on both sides of the direction perpendicular to the direction, and the data of the enlarged frame is drawn.

〔Effect of the invention〕

According to the present invention, drawing 1 in the vicinity of the frame bowl field? Since the turns are exposed twice, the drawbacks of the rusk scan method, such as the low dose fit at the start and end points of the scan, and the low dose especially for small-sized beams, can be avoided. It can be prevented. For this reason,
It is possible to reliably prevent the occurrence of constriction of the pattern, shortening of the dimension, etc., and it is possible to significantly improve the drawing accuracy. Therefore, even finer patterns can be drawn with 5T capability.

[Embodiments of the invention]

FIG. 5(a) is a schematic diagram showing an example of conventional frame division, in which the drawing area is a rectangular frame 21 +22, ~, 2
It was divided into n. On the other hand, in this embodiment, as shown in FIG. 5 and 6), each of the frames 21, 22, . , ~,6n were set. Here, the width Δ is equal to the slope width of the electron beam profile, that is, the minimum beam width. 3(a)-(C) and FIG. 4(a)-(
When drawing was performed in the same manner as described using C), the following results were obtained. In other words, Fig. 6 (
The pattern to be drawn as shown in a) was drawn on the enlarged frame data as shown in Φ) in the figure. As a result, the pattern actually drawn and formed (pattern after development) is
As shown in Figure 6(C), there is no constriction in the pattern (
This pattern matched well with the pattern a). Similarly,
When the pattern shown in Fig. 70 was drawn as shown in Fig. 70), the pattern actually drawn and formed was shown in Fig. 70.
As shown in the figure, there was no shortening of the pattern size, and the pattern matched well with the pattern shown in the same figure <=>.

Thus, according to the method of this embodiment, it is possible to form a pattern with high drawing accuracy without causing constriction or shortening of the pattern.

Also, the expanded width 2Δ of the frame is '/
Since it is extremely short, 100 or less, it is possible to easily perform drawing with enlarged frame data without any inconvenience.

Note that the present invention is not limited to the embodiments described above. For example, in a rask scan type electron beam exposure apparatus, the dose becomes small at the start and end points of the beam scan of a drawn pattern, so a compensation means may be provided to increase the dose at these points. in this case,
If the above starting point or ending point exists near the frame boundary,
There is a possibility that the dose amount in this portion may become excessive. Therefore, when the present invention is applied to an apparatus equipped with the above-mentioned compensation means, it is sufficient to prevent the above-mentioned compensation means from operating in the double exposure area, that is, within the 2Δ region shown in FIG. 6(b). .

Further, the enlarged width Δ of the frame is not necessarily limited to the minimum width of the electron beam, but may be determined as appropriate depending on the beam profile, other conditions, etc. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram for explaining the conventional electron beam lithography method using the rusk scan method, Fig. 2 (,) (b) is a schematic diagram showing the electron beam profile, and Figs. 3 (a) to (
C) and FIGS. 4(a) to (C) are schematic diagrams for explaining the problems of the conventional method, respectively, and FIGS. 5(a) and (b) are for explaining one embodiment of the present invention. 6(a) is a schematic diagram showing an example of conventional frame division, FIG. 6(b) is a schematic diagram showing an example of frame division in the embodiment, and FIGS.
(c) and FIGS. 7(a) to (C) are schematic diagrams for explaining the operation of the above embodiment, respectively. 1... Sample, 2 + jl r 22 + ~, 2
n... Frame, 3... Electron beam, 4... Deflection plate, 5... Chip, 6+61 +62r~, 6n・
・Enlarged frame. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 (a) (b) Figure 3 Figure 4 Figure 6 Figure 7

Claims (2)

[Claims] (1) Divide the drawing area into rectangular frames and
In an electron beam lithography method in which lithography is performed by raster scanning an electron beam in a direction perpendicular to the longitudinal direction of the frame, an enlarged frame with a predetermined width Δ added to both sides of the frame in a direction perpendicular to the longitudinal direction of the frame is used. is set in advance, and the data of this enlarged frame is drawn. (2) The electron beam drawing method according to claim 1, wherein the enlarged width Δ of the frame V-frame is set to be substantially equal to the minimum width of the electron beam.